The purpose of this project is to continue and extend our research on the development of young children's knowledge about the mind. During the current grant period we have elaborated a theory of this development. It asserts that children begin their discovery of the world by learning that they and other people have internal experiences that connect them cognitively to objects and events-- experiences like perceiving objects, knowing them, wanting them, fearing them, etc. Later, they gradually come to understand the these cognitive connections engender inner mental representations of their external objects, and consequently that it is possible for the same object to be represented in different, seemingly contradictory ways: for example, as A in appearance but R in reality (appearance-reality), or a A1 by one person but A2 by another (perceptual, cognitive, and affective perspective-taking). Most of the proposed studies are designed to test the theory; all of them are intended to advance our knowledge of this important area of cognitive development. What we learn about children's limitations in understanding the appearance-reality distinction and perspectives may have health- related applications. For example, children may be all too willing to try drugs or alcohol, engage in dangerous activities, be easy prey to persuasive appeals, etc., partly because they cannot easily imagine that things that seem or appear pleasant could in reality be unpleasant (appearance-reality), and that how things feel now may be different from how they feel later (perspectives).